There is an iphone that works in Dominican Republic? Or none of this models will be available for that country.

If the country you want to use it in has carriers that support eSIMs then you could.

Also the warranty is only good in the country you purchased the phone in.

Look at this page to see if there are carriers that support eSIMs in the Dominican Republic-

Find wireless carriers that offer eSIM service - Apple Support

Only the U.S. models don't have a SIM tray. iPhones sold outside the U.S. will still be able to use SIM cards.